In these years, application of a liquid crystal display device to a word processor, a laptop personal computer, a pocket television, etc. has been rapidly advanced. Among the liquid crystal display devices, a liquid crystal display device of a reflection type can show display using ambient light without the use of a backlight, and consumes a smaller amount of power compared with a liquid crystal display device of a transmission type. Thus, the liquid crystal display device of the reflection type has been recently used for a portable game device, a PDA (Personal Digital Assistant) device, etc.
Further, in these years, a liquid crystal display device of a transflective type has been developed, in which a liquid crystal display screen can show both reflection display and transmission display. The liquid crystal display device of the transflective type can achieve fine display without consuming a large amount of power by showing the reflection display using ambient light when the surroundings are bright; and can achieve fine display by showing the transmission display with turning on a backlight when the surroundings are dark. Thus, the liquid crystal display device of the transflective type has come to receive attention particularly as a display for a cellular phone.
A conventional liquid crystal display device of the transflective type generally has a system as shown in Japanese Unexamined Patent Publication No. 101992/1999 (Tokukaihei 11-101992, published on Apr. 13, 1999; corresponding to U.S. Pat. No. 6,195,140). The liquid crystal display device disclosed in Tokukaihei 11-101992 has an arrangement as shown in FIG. 22. Namely, a plurality of gate bus lines 101 and a plurality of source bus lines 102 cross with each other, and, in a matrix manner, a pixel electrode is provided via a switching element (not shown) at each intersection where the plurality of gate bus lines 101 and the plurality of source bus lines 102 cross.
Further, the pixel electrode is composed of a transparent electrode and a reflective electrode that are electrically connected with each other. These electrodes are arranged in the following manner. A transparent insulating layer (not shown) is formed on the gate bus line 101, the source bus line 102, and the switching element. On the transparent insulating layer, the transparent electrode and the reflective electrode are sequentially formed, allowing a part of the reflective electrode to have an opening for light transmission. In the liquid crystal display device, a region where the reflective electrode is formed (reflection region; shown as the shaded portion in FIG. 22) 103 shows reflection display; while the opening provided in the reflective electrode (transmission region; shown as the dotted portion in FIG. 22) 104 shows transmission display.
However, in the conventional liquid crystal display device of the transflective type, each pixel area is composed of the reflection region 103 and the transmission region 104, and each pixel area is surrounded by an inter-pixel region that insulates adjacent pixels from one another. The inter-pixel region is formed in an etching step for forming the transmission and reflection regions, and thus requires a width of at least about 5 μm.
Since the inter-pixel region does not contribute to the screen display, a larger ratio of the inter-pixel region with respect to the display screen decreases an aperture ratio. In particular, when a pixel size decreases in a liquid crystal display panel of high definition, the ratio that the inter-pixel region occupies the display screen accordingly increases. Thus, in a liquid crystal display panel used for a cellular phone display, etc., the inter-pixel region occupies about 20 percent of the entire display screen, resulting in that the aperture ratio of the liquid crystal display panel is limited up to about 80 percent.